1. Field of the Invention
This invention relates generally to electronic keyboards and associated key cap assemblies and methods of assembling keyboards and, more particularly, to key cap assemblies and methods of permanently mounting key cap assemblies for sliding movement within key holes of a keyboard.
2. Description of the Related Art Including Information Disclosed Under 37 C.F.R. 51.97-1.99
Electronic keyboard assemblies of the type having a planer array of key switches overlain by an associated array of key holes of a keyboard are well known.
Key cap assemblies are mounted for limited sliding movement within the mating key holes to engage and actuate the key switches. The key switches are temporary contact switches that are spring biased to raise a switch actuator and associated key cap assembly to a home position after being released.
The key cap assemblies have a cap which bears a number letter, word or other designation or indicia identifying to the user the function performed in response to actuation of the key. Sometimes the same key switch and its key hole location are associated with different functions and thus require key cap assemblies with different indicia.
It is important that indicia on the key cap assemblies is durable and that the mounting of all key cap assemblies within their related key holes is permanent (i.e. the key cap assemblies can be readily removed by the user from the top of the keyboard only with special tools, not provided, if at all. ) Otherwise, the indicia for a given function can be obscured or lost from wear, or the key cap assemblies can become lost, stolen for purposes of gain, or worse, exchanged for key cap assemblies with incorrect indicia for purposes of sabotage or by mistake by unauthorized personnel.
In known keyboards, all the key cap assemblies are bottom mountable only and must all be inserted into their associated key holes from the bottom of the keyboard. A fixed nonmovable collar or other fixed blocking mechanism is provided to engage with the bottom of the keyboard and thereby permanently prevent removal from the top of the keyboard. The same fixed collar prevents all the key cap assemblies of the keyboard from being installed from the top of the keyboard. Disadvantageously, once the key cap assemblies are inserted into the keyboard at the manufacturing facility, and the housing is closed, the key cap assemblies are permanently set into place. The key cap assemblies with fixed blocking mechanisms cannot be removed or installed without disassembling the housing, and thus the key cap assemblies and the designations they carry cannot be readily changed at the customer site.
Many devices which employ keyboards perform different functions in different ways depending on how they are programmed. For example, activation of a given key may cause a message to be recorded if activated when the keyboard device is in one program mode, while activation may cause a message to be played back when the device is programmed in a different mode. Thus, while the physical layout of the keyboard remains the same, indicia of the cap (i.e. "record" or "play") must change depending upon which function the particular key is to perform when actuated.
Often, the particular function for a given key is not known until the device is installed at the customer site or needs to be changed after initial installation. Unfortunately, since known permanently installed key cap assemblies can be inserted only at the manufacturing facility, the only way in which key cap assemblies have been permanently installed is by installing all of them at the manufacturing facility by inserting them into the key holes from the bottom of the keyboard. None are permanently installed at the customer site, and if it is desired to change a key cap assembly after delivery to a user site, the entire keyboard must be returned to a remote facility equipped to open the housing and dissemble the entire keyboard from the key switch array.
While there are known key cap assemblies which are not permanently mounted and can be removed and reinserted from the top of the keyboard, they leave open space between the cap assembly and the key holes with which they are mated and thus, render the components within the keyboard housing susceptible to damage by dust, dirt, water or other debris.